National Instruments GPIB-SCSI-A, Руководство пользователя

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S Mode Functions Chapter 5
GPIB-SCSI-A User Manual 5-70 © National Instruments Corp.
rpp - Request (Conduct) a Parallel Poll
Type: Parallel Poll function
Purpose: Use
rpp
if you want to conduct a parallel poll to obtain
information from several devices at the same time.
Format:
Bit 7 6 5 4 3 2 1 0
Byte
0 Opcode = D0H
1 Reserved
2 Reserved
3 Reserved
4 Reserved
5 Reserved
Remarks:
rpp
causes the GPIB-SCSI-A to conduct a parallel poll of
previously configured devices by sending the IDY message
(ATN* and EOI* both asserted) and reading the response from
the GPIB data lines. The GPIB-SCSI-A pulses the IDY
message for greater than or equal to 2
µ
sec and expects valid
responses within that time. It remains Active Controller
afterward.
The GPIB-SCSI-A returns the Parallel Poll Response (PPR)
following the poll in the form of a 1 byte binary number
during the Data In phase.
If this is the first function you call that requires GPIB
Controller capability and you have not disabled System
Controller capability with
rsc
, the GPIB-SCSI-A sends
Interface Clear (IFC*) to make itself Controller-In-Charge
(CIC). It also asserts Remote Enable.